Binding of the host-specific toxins from Helminthosporium maydis race T and Phyllosticta maydis to mitochondria isolated from Zea mays
Helminthosphorium maydis race I and Phyllosticta maydis, the causal agents of southern and yellow corn leaf blights, respectively, produce host-specific toxins. The toxic specificity of these natural products is identical to the host-specificity of the pathogens for certain varieties of corn. Susceptible genotypes carry the Texas type of cytoplasmic male sterility. Isolated mitochondria from susceptible plant species are highly sensitive to these toxins, whereas other plant species, including resistant corn varieties, and their mitochondria are not. The mitochondrion may be the primary cellular site of action for these toxins. The toxins from H. maydis and P. maydis were tritiated by reduction with borotritide salts. The labeled products had a high specific activity (3.8 to 8 Ci/mmole), high biological activity, and specificity identical to that of the native toxins. A filtration binding assay was developed to investigate the binding characteristics of these labeled toxins to isolated mitochondria. Mitochondria isolated from both cytoplasmic male sterile (Texas) and normal corn demonstrated similar binding characteristics including ligand displaceable binding with both labeled toxins. Ligand displaceable binding was also detectable in mitochondria from soybeans, a nonhost plant for these fungi. The ability to displace the bound labeled toxins was generally correlated with the biological activity of the competing toxin. The results of this study suggest that a receptor site hypothesis for the mode of action of these toxins may not be valid.
- Research Organization:
- Nebraska Univ., Lincoln (USA)
- OSTI ID:
- 6789942
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
MITOCHONDRIA
CONFIGURATION INTERACTION
RECEPTORS
RADIOASSAY
TOXINS
GENOTYPE
HELMINTHS
MAIZE
TRITIUM COMPOUNDS
ANTIGENS
CELL CONSTITUENTS
CEREALS
GRASS
LABELLED COMPOUNDS
MATERIALS
MEMBRANE PROTEINS
ORGANIC COMPOUNDS
ORGANOIDS
PLANTS
PROTEINS
TOXIC MATERIALS
550601* - Medicine- Unsealed Radionuclides in Diagnostics